Derivative Instruments and Hedging Activities (Narrative) (Details) MMBbls in Millions	3 Months Ended
	Oct. 31, 2017 USD ($) MMBbls	Oct. 31, 2016 USD ($)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0	$ 0
Reclassification of net gain to earnings during next 12 months	$ 24,700,000
Description of Reclassification of Cash Flow Hedge Gain (Loss)	0
Number of barrels of propane covered by cash flow hedges | MMBbls	3.2
Derivative amount of credit risk	$ 33,300,000
Derivative net liability position aggregate fair value	0
Gain or loss in earnings related to hedge ineffectiveness	0	0
Reclassification of gain (loss) to earnings from discontinuance of cash flow hedges	0	0
Ferrellgas, L.P. [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0
Reclassification of net gain to earnings during next 12 months	$ 24,700,000
Description of Reclassification of Cash Flow Hedge Gain (Loss)	0
Number of barrels of propane covered by cash flow hedges | MMBbls	3.2
Derivative amount of credit risk	$ 33,300,000
Derivative net liability position aggregate fair value	0
Gain or loss in earnings related to hedge ineffectiveness	0	0
Reclassification of gain (loss) to earnings from discontinuance of cash flow hedges	$ 0	0
Crude Oil [Member]
Number of barrels of propane covered by cash flow hedges | MMBbls	0.3
Crude Oil [Member] | Ferrellgas, L.P. [Member]
Number of barrels of propane covered by cash flow hedges | MMBbls	0.3
Propane commodity derivatives [Member] | Interest Expense [Member] | Ferrellgas, L.P. [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0	0
Interest Rate Swap [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0	$ 0